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Groups > comp.lang.c > #63057

Re: counting bytes

From David Brown <david.brown@hesbynett.no>
Newsgroups comp.lang.c
Subject Re: counting bytes
Date 2015-06-08 09:05 +0200
Organization A noiseless patient Spider
Message-ID <ml3eom$v3v$1@dont-email.me> (permalink)
References (4 earlier) <cthalvFnjb7U1@mid.uni-berlin.de> <ml1h2m$1dc$1@dont-email.me> <87eglns3jc.fsf@kst-u.example.com> <ml2bjj$5jb$1@dont-email.me> <87a8wbry3h.fsf@kst-u.example.com>

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On 07/06/15 23:46, Keith Thompson wrote:
> David Brown <david.brown@hesbynett.no> writes:
>> On 07/06/15 21:48, Keith Thompson wrote:
>>> David Brown <david.brown@hesbynett.no> writes:
>>> [...]
>>>> _Static_assert(sizeof(int32_t) == 4, "Checking char size");
>>>
>>> The string says "Checking char size", but it's checking the size of
>>> int32_t.
>>>
>>> The only way int32_t can have a size other than 4 bytes is if
>>> CHAR_BIT > 8.  You can replace the above with:
>>>
>>> _Static_assert(CHAR_BIT == 8, "Checking CHAR_BIT");
>>
>> That's pretty much exactly what I wrote - you must have missed that part
>> of my mail.
> 
> Ah, so you're checking sizeof (int32_t) for the purpose of checking that
> CHAR_BIT==8.  I did figure out that that's the consequence of that
> check, but it wasn't obvious (at least to me) that that was what you
> meant; I assumed that there was some sort of typo.
> 
> If you want to check that CHAR_BIT==8, why not just check that
> CHAR_BIT==8?
> 
>> The only reason for using a check with sizeof(int32_t) rather than
>> CHAR_BIT is to save yet another include file.
> 
> Not worth it IMHO.
> 

I was merely offering an alternative - and if it was unclear, then I
agree it is a bad choice.  In hindsight, it was a bad idea - it has
distracted the thread from my main point, which is the use of static
assertions to check that you've got your sizes and alignments the way
you want them.

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Thread

counting bytes bilsch01 <king621@comcast.net> - 2015-06-06 04:58 -0700
  Re: counting bytes Bartc <bc@freeuk.com> - 2015-06-06 13:05 +0100
    Re: counting bytes bilsch01 <king621@comcast.net> - 2015-06-06 05:24 -0700
      Re: counting bytes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-06-06 05:41 -0700
        Re: counting bytes Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-06 14:00 +0100
      Re: counting bytes Bartc <bc@freeuk.com> - 2015-06-06 13:52 +0100
      Re: counting bytes Lew Pitcher <lew.pitcher@digitalfreehold.ca> - 2015-06-06 10:27 -0400
        Re: counting bytes jt@toerring.de (Jens Thoms Toerring) - 2015-06-06 22:31 +0000
          THANKS EVERYBODY FOR THE INFO bilsch01 <king621@comcast.net> - 2015-06-06 23:35 -0700
            Re: THANKS EVERYBODY FOR THE INFO Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-07 10:08 +0100
              Re: THANKS EVERYBODY FOR THE INFO Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-06-07 09:22 -0700
                Re: THANKS EVERYBODY FOR THE INFO Ben Bacarisse <ben.usenet@bsb.me.uk> - 2015-06-07 18:07 +0100
                Re: THANKS EVERYBODY FOR THE INFO Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-06-08 04:03 -0700
                Re: THANKS EVERYBODY FOR THE INFO Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 08:12 -0700
            Re: THANKS EVERYBODY FOR THE INFO Keith Thompson <kst-u@mib.org> - 2015-06-07 08:01 -0700
          Re: counting bytes gordonb.3gcai@burditt.org (Gordon Burditt) - 2015-06-07 05:02 -0500
          Re: counting bytes David Brown <david.brown@hesbynett.no> - 2015-06-07 15:32 +0200
            Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-06-07 12:48 -0700
              Re: counting bytes David Brown <david.brown@hesbynett.no> - 2015-06-07 23:05 +0200
                Re: counting bytes Richard Heathfield <rjh@cpax.org.uk> - 2015-06-07 22:17 +0100
                Re: counting bytes David Brown <david.brown@hesbynett.no> - 2015-06-07 23:49 +0200
                Re: counting bytes Richard Heathfield <rjh@cpax.org.uk> - 2015-06-07 23:37 +0100
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 08:25 -0700
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-11 08:21 -0700
                Re: counting bytes Martin Shobe <martin.shobe@yahoo.com> - 2015-07-11 13:54 -0500
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-20 06:33 -0700
                Re: counting bytes Martin Shobe <martin.shobe@yahoo.com> - 2015-07-20 09:51 -0500
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-24 09:49 -0700
                Re: counting bytes Martin Shobe <martin.shobe@yahoo.com> - 2015-07-24 12:26 -0500
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-30 11:16 -0700
                Re: counting bytes Martin Shobe <martin.shobe@yahoo.com> - 2015-07-30 23:15 -0500
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-08-02 06:07 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-08-02 14:31 -0400
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-08-09 05:31 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-08-09 17:09 -0400
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-05 09:58 -0700
                Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-09-05 19:29 -0700
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-06 14:38 -0700
                Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-09-06 17:46 -0700
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-07 23:50 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-09-06 22:00 -0400
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-07 23:24 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-07-24 20:03 -0400
                Re: counting bytes Martin Shobe <martin.shobe@yahoo.com> - 2015-07-24 22:13 -0500
                Re: counting bytes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-25 02:22 -0700
                Re: counting bytes Martin Shobe <martin.shobe@yahoo.com> - 2015-07-25 11:39 -0500
                Re: counting bytes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-25 09:48 -0700
                Re: counting bytes Martin Shobe <martin.shobe@yahoo.com> - 2015-07-25 14:04 -0500
                Re: counting bytes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-25 14:22 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-07-25 11:07 -0400
                Re: counting bytes James Kuyper <jameskuyper@verizon.net> - 2015-07-25 12:43 -0400
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-07-25 13:32 -0400
                Re: counting bytes glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-07-25 20:14 +0000
                Re: counting bytes James Kuyper <jameskuyper@verizon.net> - 2015-07-25 17:24 -0400
                Re: counting bytes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-25 14:42 -0700
                Re: counting bytes glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-07-25 23:02 +0000
                Re: counting bytes James Kuyper <jameskuyper@verizon.net> - 2015-07-25 19:17 -0400
                Re: counting bytes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-25 16:37 -0700
                Re: counting bytes glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-07-26 06:10 +0000
                Re: counting bytes James Kuyper <jameskuyper@verizon.net> - 2015-07-26 08:31 -0400
                Re: counting bytes Bartc <bc@freeuk.com> - 2015-07-30 21:32 +0100
                Re: counting bytes raltbos@xs4all.nl (Richard Bos) - 2015-07-31 13:25 +0000
                Re: counting bytes James Kuyper <jameskuyper@verizon.net> - 2015-07-31 11:31 -0400
                Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-07-31 11:30 -0700
                Re: counting bytes James Kuyper <jameskuyper@verizon.net> - 2015-07-31 14:29 -0400
                Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-07-31 12:14 -0700
                Re: counting bytes David Kleinecke <dkleinecke@gmail.com> - 2015-07-31 17:39 -0700
                Re: counting bytes James Kuyper <jameskuyper@verizon.net> - 2015-07-31 23:32 -0400
                Re: counting bytes David Kleinecke <dkleinecke@gmail.com> - 2015-08-01 16:41 -0700
                Re: counting bytes James Kuyper <jameskuyper@verizon.net> - 2015-08-01 20:23 -0400
                Re: counting bytes Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-07-31 11:01 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-07-25 19:42 -0400
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-30 12:16 -0700
                Re: counting bytes Bartc <bc@freeuk.com> - 2015-07-30 22:04 +0100
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-08-02 06:10 -0700
                Re: counting bytes David Kleinecke <dkleinecke@gmail.com> - 2015-07-25 19:10 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-07-25 22:16 -0400
                Re: counting bytes David Kleinecke <dkleinecke@gmail.com> - 2015-07-25 19:46 -0700
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-30 11:52 -0700
                Re: counting bytes raltbos@xs4all.nl (Richard Bos) - 2015-07-31 08:51 +0000
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-08-02 06:19 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-08-01 09:39 -0400
                Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-08-01 13:06 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-08-01 20:43 -0400
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-08-02 06:52 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-08-02 15:14 -0400
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-08-09 07:54 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-08-09 16:43 -0400
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-09-05 10:48 -0700
                Re: counting bytes Richard Damon <Richard@Damon-Family.org> - 2015-07-11 17:50 -0400
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-20 06:36 -0700
                Re: counting bytes raltbos@xs4all.nl (Richard Bos) - 2015-07-20 15:14 +0000
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-24 09:38 -0700
                Re: counting bytes raltbos@xs4all.nl (Richard Bos) - 2015-07-25 19:12 +0000
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-30 12:18 -0700
                Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-07-11 17:03 -0700
                Re: counting bytes glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-07-12 00:15 +0000
                Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-07-11 17:42 -0700
                Re: counting bytes glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-07-12 02:46 +0000
                Re: counting bytes James Kuyper <jameskuyper@verizon.net> - 2015-07-12 12:33 -0400
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-20 06:48 -0700
                Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-07-20 11:18 -0700
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-24 09:58 -0700
                Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-07-24 11:14 -0700
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-07-30 11:02 -0700
                Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-07-30 13:10 -0700
                Re: counting bytes Tim Rentsch <txr@alumni.caltech.edu> - 2015-08-01 10:53 -0700
                Re: counting bytes Keith Thompson <kst-u@mib.org> - 2015-06-07 14:46 -0700
                Re: counting bytes David Brown <david.brown@hesbynett.no> - 2015-06-08 09:05 +0200
  Re: counting bytes Siri Cruz <chine.bleu@yahoo.com> - 2015-06-06 05:06 -0700
  Re: counting bytes bartekltg <bartekltg@gmail.com> - 2015-07-26 00:58 +0200
    Re: counting bytes bartekltg <bartekltg@gmail.com> - 2015-07-26 01:00 +0200

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